Prior art terminal assemblies have included both terminal covers and/or fences which are designed to protect the terminals from physical damage as well as electrically isolating the terminals for safety concerns. While these prior art terminal assemblies have been effective, there is always a need to improve the safety of these terminal assemblies. The prior art terminal assemblies can permit an individual to operate the compressor without the installation of all of the various safety devices designed into the terminal assembly. Without these safety devises installed, the operation of the compressor can be achieved while having the individual terminals exposed creating a hazardous situation. The present invention eliminates this possibility by combining a unique terminal with a unique electrical plug.
Typically, a prior art hermetic terminal is installed in a hole formed in the hermetic shell of a hermetic compressor so that current may be carried to the motor of the compressor from an external source of power. The prior art terminals comprise a body welded or secured to the shell of the compressor and a plurality of conductor pins extending through the body. In order to seal and electrically insulate the conductor pins relative to the body, a glass-to-metal seal is employed, having an epoxy and/or silicone rubber overcoating. Both the inner and outer ends of the conductive pins may be provided with conductor tabs so as to facilitate connection to the external source of power on the outside of the shell and to the compressor motor on the inside of the shell.
One problem associated with these prior art terminals is that in response to unexpected abnormally high over current conditions e.g., due to ground fault or a short circuit, the conductor pins may heat up to the point of melting the conductor pins themselves or the surrounding glass-to-metal seals, thereby resulting in the failure or leaking of the hermetic terminal and thus the hermetic shell.
One method for preventing occurrence of the failure or leaking of the hermetic terminal is to use a fuse-like link within the conducive path of each conductor pin. Prior art hermetic terminals include pins which incorporate a reduced fuse-like area located on the segment of the pin which is positioned on the inside of the hermetic shell or on the segment of the conductor pin which is positioned on the outside of the hermetic shell. When an over current condition of the compressor occurs, this fuse-like area of the conductor pin separates. The fuse-like area of the conductor pin in prior art compressors is typically located on the inside of the shell for safety reasons. If the fuse-like area were located on the outside of the shell, the separating of the fuse-like area could free the power line which provides power to the conductor pin and allow this wire to short out against the shell and/or the other conductor pins or power lines. When the fuse-like area of the conductor pin is located on the inside of the shell, this separating of the fuse-like area of the conductor pin effectively disconnects power to the compressor but it also leaves the opportunity for the pin to be pushed out of the body of the terminal causing the leakage or failure of the hermetic terminal and thus the hermetic shell. Some prior art terminals have incorporated a stop flange integral with the fuse-like link in an attempt to insure that the pin will not be forced out of the body and cause blow out of the terminal. However, these types of terminals have a tendency to separate from the fused glass seal simultaneously with the separation of the conductor pin in an over current situation which then causes the leaking of the hermetic shell.
Another problem associated with the prior art terminals is that of corrosion. The conductor pins are normally constructed from stainless steel due to its corrosion resistance. Since one end of the conductor pins will be extending outside of the hermetic shell, corrosion of the exposed ends becomes a possibility if the conductor pins are not constructed of a corrosion resistant material. In addition, it is the usual practice to weld tabs or spades to the exposed outer ends of the conductor pins, which tabs or spades are adapted to receive terminal clips carried by the wiring which extends from the source of electrical power. This mechanical interconnection which exists between the terminal clips and the conductor pin tabs or spades is an additional area which is susceptible to corrosion and therefore requires some form of sealant.
Accordingly, there is a need for providing a conductor pin having an integral fuse-like link which maintains the integrity of the hermetic shell upon failure of the fuse-like link. Preferably, the fuse-like link would also be located on the outside of the shell with provisions being made to insure that upon melting of the fuse-like link, the power line leading to the fuse-like link is prevented from shorting out against any of the other compressor components. In addition, the outside connection of the conductor pins with the terminal connector should be provided with a sealing system which keeps both moisture and debris from degrading the mechanical connection between the conductor pin and the terminal connector.